Electrically-controlled cable stripping machine



ELECTRICALLY-CONTROLLED CABLE STRIPPING MACHINE Filed Aug. 28, 1950 K. J. WELLS March 9, 1954- 2 Sheet s-Sheet l Inventor: Kenheth d. Wells,

His AEt or'ne y.

arch 9, 1954 WELLS 2,671,363

ELECTRICALLY-CONTROLLED CABLE STRIPPING MACHINE Filed Aug. 28, 1950 2 SheetsSheet 2 Inventor; Kenneth J. Wells,

' l-lis Attorne g.

Patented Mar. 9, 1954 -ELE G'I'RICALLY- CONTROLLED. CABLE .T'STRIPPING MACHINE [Application August 28, 195 0, Serial N; 181;? 92

.2 7. Glaims. 1 inventionrelates todevicesior *remdving insulation 'from""eiectrical conductors and'-more particularly toa device of this nature which is automatically controlled" to prevent c'utting any of the "conductor surrounded "by the "insulation.

the electrical industry, both in manufa ctairl ing and in-instal1'ation-' work," there -:on'stan'tly arises the necessity of removing insulatiori from --the*ends of electrical 'cond-uctors in "order' that the conductors 'may-besuitably connected to uti- -lization*-devices. When insulation is stripped from conductors by manualmethods the process is "tedious 'and' time-consuming. Furthermore, evenif the'insulationis stripped from the conductors by 'means of stripping machines oii the 'type heretofore in use, unsatisfactory resultsare often obtained" due to the-fact that-cable stripfping devicesin accordancewith the' prior art have frequentlybeen inaccurate' with t-he =result that a portion of the conducting material is cut away along with the insulation.

It 'canbe seen, "therefore, that a cable stripping machine" which willautomatically strip 1 insulation from a conductor without danger-'of cutting *i'ntothe conducting material would be ofgreat.- benefit to the electrical industry.

It is anobjectof myinvention;therefore;- to "provide a' new and'improved insulation stripping *machine which will efliciently remove insulation %from an electrical conductor without removing;

any of the conducting material surrounded'by the'insulation.

It "is afurther object of my invention to i" provide a new and improved insulation stripping machine in'which the stripping operation'isan-z tomatic'allydiscontinued'instantaneously when a predetermined amount of I insulation has been stripped from the conductor member.

It is a further object of my invention to provide an insulation stripping machine which is regu-r "lated by an electrical circuit insuch-manner'that the strippingmechanism is-retracted instantaneouslywhen a predetermined amountofinsula- 'tion has been removed.

Inaccordance with these objectives my: inven-i tion providesacable stripping machine in'wh-ich 'the' cutting knives which strip'the insulation complete an electrical circuit as "soon as 'they touch 'the conducting member, with the: result that the cutting mechanism is instantaneously:

retracted from cutting engagement.

The features of this'inventionwhich I believe to'be novel are setforth with particularityinthe appended claims. Myinvention itself; however, eam as to "its organization and use-,"--together withi (Cli:-81-=-.9.5'1)

9 further 'obje'cts and advantages i thereof, =ianay best-be understood by referenceto the follow'ing descriptiom taken connection-with the-accom- -panying drawing imWhich- FigJ 1': isa v-iew i)f a -"cable-strippingmechanism inaccoidance with my inve'n'tion; while-"Fig. 2 "is" a wiri-ng 'diag'ram iafi an electrical contrblcircuit Which-may beflused in conne otion with the calleile-=' stripping machine of Fig:' 1.

Referring now to the drawing; th'ere iis slaown a cable l having a covering: oi insulation 1% and a'center-conductor member 3. 'The -cable I is =held in pos'ition by-a e'ollet fl h'aiving a plurality of --'-jawmembers 5- which g ripflthe came and tiold it 5 rigidly in'pdsition. The-'colleti 4;'may be *ofi nny suitable type; and-forms -'no p'art oi th-is invention. It may-beman-uaHy tightened' or it may be actuated by= air or 'l hid pressurefiifii'desired. A portion of thecab1e protimoles througlrrthe jaws 5*bf the amer 4g this portion ofiithetcable having the end from which the i-nsulatiomisrto be stripped.

'Ihe cable stripping devicewhich wilbibeirle- ---scribdzhereinaftenin more detail rotatesswith a shaft, 6, which may be driven by anys-zsi-iitable poweF-device; such::asfifom-exampleeam electric motor.

A-eollafi mskeyed or titherwise Arigidly attached *to shaft 8 and-rotates therewith. flA pairmfmutting k'nives 8 and -9 are' respectively mounted; at theendsof lever *members 1 0: and 5H -'-'which;1are -pivota11y=mounted= with re'spectitoacotlar member 1. "Collar" menriberl T is:providedswitlfitwowapertur'es -l zaat' diametrically: oppositelpositinnsgsand lever members-* mand il heachr' respectivelysp'ass I throughone'otthe apertures 12*; eachfileuenmember being pivotally connected to =theiicol=lar membei 1:. by meansbf a pin' l 3.

*A'cone shaped: member :1 4srisfslidabhemounted on 'shaft 6, theapex of the coneishapee being direeted toward the lever imembers 10 and :U. A spring 1 5 is e'onnectedvbetweemtwor coimespondingpoints om leveu members Band 1| ear-espectively;- on an oppositelside berpivotf pins '1 kthan thecutting: knives; 84am Srtoznormaliymnaintain the cutting kn ives G andi Enut-of ic'uttingiengage- 1 ment-withithecable .I. :flEherendssofialevemmem- -'-bers 'i'l [land 1 Lara ea'chrespecttveiy provid'edwith "roller:members i 6? and? SI 1 fomengagementewith the surface of conei Mp'as willsbef hereinafter described-linzmore detail.

-when -cone 1 mis caused-totmove axially along mshaft 6}:lever members :10 Sand '1 lsarezcausd to -pivot about pinsi 13;: with thei result thatz'cutting knives Hand 9 whicmare attachedutosilevers I0 and H are caused to move into contacting relation with the insulating material which is to be cut.

Axial motion of cone I4 is caused by its engagement with crank member I8. Crank I8 is rigidly attached to one end of a shaft I9, the other end of the shaft I!) being rigidly attached to a second crank member 20 at right angles to crank |8. Crank 20 is pivotally connected to a connecting rod 2| attached to a piston 22 inside of a cylinder 23. Piston 22 is caused to move in cylinder 23 by air pressure admitted to the cylinder through conduits 24 and 25, respectively. Valves 26 and 2! are provided in air supply conduits 24 and 25, respectively, valves 26 and 21 being respectively controlled by electrical solenoids 28 and 29. When solenoid 28 is energized, as will be hereinafter described, valve 26 is actuated to admit air through conduit 24 to cylinder 23, thereby causing a downward motion of piston 22, with respect to the view shown in the drawing. When solenoid 29 is energized, valve 21 is actuated in such manner as to admit air through inlet conduit 25 to cylinder 23 thereby causing a motion of piston 22 in an upward direction, with respect to the view shown in the drawing. In order to provide a cushioning effect on the action of the air cylinder when the piston 22 moves in an upward direction, with respect to the view shown in the drawing, a hydraulic dashpot device 30 is provided adjacent air cylinder 23. The dashpot piston is mechanically connected to connecting arm 2| by an arm 3|. The dashpot 30 provides a damping action in one direction only, namely, as will be explained hereinafter, the direction in which the cutting knives 8 and 9 are being fed into the insulation.

It can be seen that when piston 22 moves upwardly in air cylinder 23 due to admission of air through conduit 25, connecting rod 2| also moves upwardly, causing crank 28 to move in a clockwise direction. This motion of crank 20 causes shaft l9, to which crank 20 is rigidly connected, to move in a clockwise direction also, carrying with it crank l8. Motion of crank |8 in a clockwise direction with respect to the view shown in the drawing causes the roller 32 at the end of crank I8 to abut against the surface of cone l4, causing cone [4 to slide axially along rotating shaft 6. Motion of cone l4 axially toward the cable causes levers I and II to pivot about pins l3, as has been hereinbefore described, with the result that rotating cutting knives 8 and 9 contact the insulating material and begin to strip the insulating material from the conductor.

In order to provide electrical contact between the end of the rotating mechanism and the cable, and in order to provide mechanical support for the free end of cable i which is having its insu lation stripped off, an assembly is provided at the end of shaft 6, which will now be described.

The outer end of shaft 6 toward the cable is provided with a recessed portion 33. A pin 34, having a diameter slightly less than recess 33 to provide for easy axial movement of pin 34, is adapted to be positioned in recess 33. Metal bushing 35 is insulatingly connected to pin 34 by an insulating pin member 36 which fits into a recess in the outer end of pin 34, insulating pin member 36 being provided at its other end with an enlarged head portion which is adapted to fit into a mating recess in bushing member 35. Thus, bushing 35 is insulatingly connected to pin 34, with insulating pin 36 serving to insulate metallic bushing 35 from the shaft 6 and collar 4 member I. The bushing 35 is provided at its end adjacent the cable with a recess 31 containing a spring 38 and a spring-biased contact point 39. Contact point 39 establishes electrical contact between metallic bushing 35 and the conductor 3 of cable I, spring 38 maintaining contact point 39 in engagement with conductor 3.

A set screw 40 is provided on shaft 6 adjacent the interior recess 33 to permit tightening pin 34 to any desired position within the recess 33. This provides a means by which the length of pin 34 projecting into recess 33 can be adjusted as desired in order to adjust the length of the cable I which projects beyond the collet 4, thereby regulating the amount of insulation which is stripped off the cable.

Collar is provided with a conducting ring 4| on its radially outer edge, ring 4| being separated from the main body of collar 1 by a circumferential insulating strip 42 positioned radially inwardly of conducting strip 4|. A collector brush 43 bears against conducting strip 4|, with brush 43 being connected to the grid of a thyratron control tube, as will be explained hereinafter. Conducting strip 4| is conducted by an electrical lead 44 to metal bushing member 35, which is connected through contact point 39 to conductor 3 of cable I. Thus, when contact point 39 is in contacting relation with conductor 3 of cable I as shown in the drawing, conductor 3 is conductively connected through lead 44 and contact strip 4| to the grid of a thyratron control tube, as will be explained in more detail hereinafter. The metal knives 8 and 9 are connected to ground through the frame of the machine. It can be seen, therefore, that when the cutting knives 8 and 9 contact the conductor 3, the conductor 3 will then be grounded, and, as will be more fully explained hereinafter, the grid of a thyratron gas control tube which controls the motion of cone I4, is likewise placed at ground potential. Thus, it can be seen that the cutting knives 8 and 9 operate as a switch to energize an electrical circuit which controls the operation of cone I4 in such manner that cone I4 is retracted instantaneously when cutting knives 8 and 9 contact conductor 3.

There are also shown in Fig. 1 two auxiliary switch devices which are mounted adjacent the linkage system which operates cone l4. These switch devices include a switch 45 positioned adjacent crank arm l8, switch 45 being caused to open when cutting knives 8 and 9 separate, and an adjustable stop or limit switch 46 positioned adjacent crank arm 20. When crank arm |8 moves in a counterclockwise direction due to a downward motion of piston 22 in cylinder 23 concurrently with the separation of the knife blades 8 and 9, switch 45, which may be a microswitch, is caused to open. Similarly, when crank arm 28 moves in a clockwise direction upwardly to a predetermined point, it will abut against adjustable stop 46 and accomplish the same electrical purpose as is accomplished when knife blades 8 and. 9 contact copper conductor 3; namely, solenoid 28 will be energized in such manner as to cause a downward motion of piston 22. Thus, adjustable stop 48 functions as a limit switch to prevent overtravel of the cutting knives 8 and 9. The adjustable stop may be adjusted in accordance with the thickness of insulation being stripped at any particular time. The electrical functions of switch 45 and adjustable stop 46 will be described hereinafter more completely in connection with a discussion v5.01: :the-j electrical :wirin .7 connection with -'Fig.t .2.

= winding and a secondary winding 54. :zA.f1111- waverectifiertube 55-has its two anodes 56, and .Ji'h'respectively, connected to: opposite sends: of transformer secondary 52. The filament of-c'ath- I ode :58 of tube .55 isenergizedby secondaryztransformenwinding- 5i; Cathodetli isconnected to -.;the.: grounded; midepoint of --secondarywinding 52.-through a series resistance 5!. and 31.111213/1181 resistance-capacitance filter, comprising vpiresistance 59 in parallel with capacitance-:60.

PTwov other, electronic tubes are. employed in;

dzthevcircuit, including; a; double diode rectifier I .tube? 62 and a thyratronpgasefilled tube? 63. '.-As will be more fullyv explained hereinafter; thyra- -trongas tube 63 operates relay devices-which control solenoidsf-Zdand "29.

tube 53.

Double-diode rectifier tube 6'3 is provided with tia double-cathode :64, adouble anode--65 and a a heater filament fifi for cathode B l. Filament 5B is-energized from secondary winding 59 of transformer 41'. Cathodeii i is connected to secondary winding 52 at the same end of the winding as the connectionpoint of anode 5? of full-wave rectifier tube 5.5, through: a resistance 61.

Diode 62 is conducting on 'thehalf'cycle of applied voltage when-theend oftransformer ---secondary to-Which cathode $4; is connected 'sthroughresistance' 61 becomesnegative. At this :instant,-. ground is-positive relativeto cathode :64. .Grid 16 of gas tube .63- is: connected the 'wcircuit'nf anode :65 between resistances! 68 and :10, a point which ':is below ground potential.

Since cathode T4 lOf tube 63 is at ground potena .tiaL: itfollows that grid 16 of-gas tube 63 is main- -'tained negative with respect to cathode: M during the; half cycle when: tube'SZ' is conducting.

- Condenser H maintains grid 16 negative-with respect to cathode-l tduri-ng the half cycle. of: ap-

pliedvoltage. when tube E52. is not conducting.

Theamount of negative bias of' grid it depends upon. the relative values. of load resistors 1 68 and- 10.

.The potential. supplied toithe anode circuit '=Df diode-rectifiertube 62 isequal to part of the .motentialbetween ground. and the endoi transformer secondary 52 to which resistance 61. is connected. 'Ihetotal potentiabbetween ground and the end of transformer secondary winding -52..is. applied across the resistors Bi and 12 which -.act. asa voltage divider. Since .cathodetdand ground are connected. onopposite s'ides of re- .sistor .12,.the voltage. dropacrosslthis resistor is ...equal. to the. voltagesuppliedtothe anode cir- .cuit .of-tube 62.

.Gas -filled tube-'63 is provided with an anode "13, a cathode; 14, a filament heater 15 for cathode M, and a grid 75. "Filament heater. .15 is energized by transformersecondary 50. vAiscreen 4 grid TI connected to ground may also .be. used .if: desired. A by-pass condenserlB is connected between grid 16. and ground. A. current+lirniting resistor 69 isrplaced'in series with gridf'lii' of vtubef63' in' accordance'with' conventional; prac- ""tice.

;'..diagram;:.describedi in The function of i double diode rectifier-tube 62 is to provide a suitable gridbiasfor the grid of thyratronz-gas-filled tatential. withrespect jtO .scathode l lzfromithewvcltage; drop across -resistance-capacitance..coupling 59-tt in the output circuit.- of rectifier.:tube- -55. .A- relay coil :19, .is. provided. in. seriesrwitlranode '13,. and a manually. operated switchitflfldsrhlso provided in serieswiththe relay coil liisaridanode :13, for a. purpose;;to;r:beeexplained'... hereinafter. Relay 19 controls a contact arm=.8l.=.:which bridges contacts .82 and tt-swhenvrelaydfixis not -energized and bridges contacts t l andrflitwhen relay. 79 is energized. When-=contact=..armi 8| is inthe position where-it bridges contactsthand -83, .it energizes close-solenoid- '29; and wherracontact arm 81 is intherposition where itr bridges contacts Ba -and. 85, .it energizes"release::;:sole- I noid- 28.

The operation of the :cable stripping; machine of; my invention .willi now be describedrimterms .the electrical wiring diagram shown 2.

of the. mechanical structure shown :in' Figi hand When the input transformers ll-and 48. are energized, rectifier tub'55 producesa full-wave rectified voltage acrossload resistor'fifl. Anode 13 of gas-filled thyratron tube: 53 is connectedacross one side of load I'BSlS'fiOl..59, withuthe otheris'ide of the load resistor being connected:...toi.;the grounded -mid-point gof .transformeriisecondary The cathode M of thyratron .gasz-filled. tube 83 is connected to ground. Hence,:.the;diiference of potential between:anode: .73 and'zcathode": 14 of. gas-filled tube1'fi3 is equal: tozfthe potential drop across resistor) 59in.:the: outputrcircuitc of rectifier tube .55. Grid 2? 6; of thyratrongasefilled tube derives a negative. bias .Wlth respect to cathode '54 of that tube due .to the relative. positions at which these twozelements. are connected vwith respect to the anode icircuit. ofz'dioderectifiertube 62, as has been previously-explained.

'When it is desired to begin cable.stripping operations,transformers 4?. and 1 38 areenergiaed,

thereby energizing full-wave rectifier .tllbeii55, half-wave; diode rectifier tube 62,- and thyratron -1 gas-filledtube 53. On this initialsenergization,

grid iii of gas-filled thyratron' tube..63.wil1:.be

at a negative potential with-respecttocathode 7.4, whileanode' .73 will be constantly.:at'.auposi tive potential with respect to cathode l4. "Due to the negative bias on gridl6,.there will-be no conduction in the. circuit of anode M sc-that relay. l9 will be unener'gizedand relay contact armti will be in a position .where it -bridges vcontacts 82 and" 83 to complete the circ'uitof close solenoid 2Q.

Energization of solenoid 29 actuatesvalve 21 to admit air to cylinder 23, thereby causing an upward motion of piston 22, with respect to the view shown in the drawing in Fig. 1. Upward motion of piston 22' causes upward motion-= of connecting rod 2! anda clockwise motion" of crank arm 253 which is pivotally connected" to connecting rod 2!. Clockwise motion'of" crank arm 29 is communicated through-shaft 19 to crank arm l8,'-which also then has a clockwise motion. Clockwisemotion of crank-&arm"l8,

with respectto the view showrrin-Fig. 1, causes "the rollers 32 on the endt'ofcrankarml8" to abut against cone M which is :slidably-mounted on "shaft 6. .Due to .the. motion of crank arm l8, cone -Mis caused to slide axially alongsh'aft 'o to the right, with respect to the viewjshown in. the. drawing,. itherebycausing rollers. 1| 6,..and

. l I. at; .the. "end. .oilever. armsv ".l 0 and? l I respecrollers 16 and I1 rldeup on cone 14, levers" I0 and I I are caused to have a pivotal motion about their respective supporting pins l3, causing cutting knives 8 and 9, which are respectively attached to the ends of levers I9 and H, to be forced into contacting and cutting relation with the insulation 2 of cable I. Knives 8 and 9 rotate with shaft 6 and cut into the insulation 2 until the metal knives contact the center conductor member 3.

When knives 8 and 9 contact center conductor member 3, grid 16 of gas-filled thyratron tube 63 is grounded instantaneously since, as has been previously explained, the center conductor member 3 is connected to the grid 16 through contact point 39, metal bushing 35, lead 44, conducting ring 4|, and brush 43, while the cutting knives B and 9 are connected through the collar 1 and shaft 6 to ground.

As soon as grid '16 is grounded due to the knives 8 and 9 contacting center conducting member 3, thyratron gas-filled tube 63 begins to conduct and relay '59 in the anode circuit of tube 63 is energized. Energization of relay 19 causes a motion of contact arm 8| so that it moves from the position where it bridges contacts 82 and 83 in the circuit of close solenoid 29, and instead bridges contacts 84 and 35 in the circuit of release solenoid 28. Energization of release solenoid 28 actuates valve 25 to admit air through conduit 24 to cylinder 23 in such manner as to cause a downward motion of piston 22 with respect to the view shown in the drawing. Downward motion of piston 22 causes a downward motion of connecting rod 21 and a counterclockwise motion of crank arms 29 and [8. Since crank arm I8 is then no longer bearing against cone It and is therefore no longer tending to maintain cone I l in a position where rollers 16 and H are riding on the cone surface, spring l pulls levers l9 and it back together again in such manner that cone i4 is forced back to the position where rollers l5 and IT are no longer riding on the cone surface. Cutting knives 8 and 9 are therefore retracted from cutting position.

As soon as lever it begins to move in a counterclockwise direction with the retraction of knives 8 and 9, switch 45 is actuated by the motion of crank arm 18, thereby opening-the circuit of release solenoid 28. Thus, release solenoid 28 can only be actuated when crank arm I8 is in a position corresponding to the cutting position of knives 8 and 9. As soon as the knives separate, switch 45 is opened and thereby the circuit of release solenoid 28 is opened.

Also, as has been previously explained, a stop 46 is provided adjacent crank arm 29 so that if crank arm 20 moves too far in a clockwise direction, it will abut against stop member 46 and ground grid 16 of thyratron gas-filled tube 63. Stop member 46 is connected to the grid 16, and crank arm 29 is connected to ground. Stop member -45 is therefore in effect a limit switch to prevent over-travel of crank arm 20. Normally, of course, cutting knives 8 and 9 will contact conductor member 3 and ground grid 16 before crank arm 20 is able to come in contacting relation with stop member 55. Stop member 46 is adjustable and may be adjusted in accordance with the thickness of the insulation which is being stripped.

A further feature is the provision of a manual switch 86 which permits manual grounding of grid 16, to thereby permit manual operation of a switch for actuating release valve 28, rather than depending upon the operation of the cutting knives 8 and 9 to efiect grounding of grid 16. Thus, if for any reason it is desired to retract the cutting knives 8 and 9 before they have come in contact with conductor 3, switch 86 may be manually closed to ground grid 16, thus actuating solenoid 28 and causing retraction of knives 8 and 9, as has been previously explained.

After the release solenoid 28 has once been actuated due to grounding of grid 16, the circuit of anode 13 remains conducting until the anode potential is removed. As is Well known. while removal of a negative grid bias will cause a thyratron gas tube to fire and cause conduction in the anode circuit, restoration of the same negative grid bias does not stop conduction in the anode circuit, and in order to stop anode conduction, it is necessary to open the anode circuit.

Hence, if it is desired to move the cutting knives 8 and 9 back into cutting position after they have been retracted, it is necessary to open the circuit of anode 13, which may be done by actuating switch to an open position. This will cause relay 19 to be deenergized and will permit relay contact arm 8| to move to the position corresponding to the unenergized condition of relay [9, where contact arm 8| bridges contacts 82 and 83. This will close the circuit of close solenoid 29 and, as has been previously explained, will cause air to be admitted to cylinder 23, with the result that cone [4 will be moved to a position where cutting knives 8 and 9 are in a cutting position with respect to cable I.

It can be seen that my invention provides a new and improved cutting mechanism for stripping insulation from an electrical cable. In accordance with my invention, the cutting knives which strip the insulation from the cable are automatically retracted into non-cutting position instantaneously when the cutting knives contact the center conductor of the cable which is being stripped. After the cutting knives cut through the insulation up to the electrical conductor, the insulation can be removed manually. The insulation can be cut through in several places to facilitate easy manual removal of the insulation. While I have shown an embodiment of my invention in which the cutting knives are actuated by a linkage system controlled by an air cylinder, it is obvious that other means could be provided to actuate the cutting mechanism. Furthermore, while I have shown an electronic circuit using a gas-filled thyratron tube for controlling the solenoids which, in turn, control the operating mechanism for actuating the cutting knives, it is obvious that other electrical circuits could be used to control the operating solenoids, and still be within the scope of my invention.

While there have been shown and described particular embodiments of my invention, it will be obvious to those skilled in the art that changes and. modifications can be made without departing from the invention and, therefore, it is aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A device for stripping insulation from an electrical conductor comprising a rotatable shaft, a cutting device rotatable with said shaft, said cutting device being formed of an electrically conducting material, means for moving said outting device into cutting engagement with the insulation of an electrical conductor, an electrically-controlled means for retracting said cutting device from cutting engagement substantially instantaneously when said cutting device contacts said conductor member, and an electrical circuit for actuating said electrically controlled means comprising said cutting device and said conductor whose insulation is being stripped.

2. A device for stripping insulation from an electrical conductor comprising a rotatable shaft, cutting means rotatable with said shaft, said cutting means being formed of an electrically conducting material, means for moving said cutting means into cutting engagement with said insulation, and electrically-controlled retracting means for retracting said cutting means from cutting engagement with said insulation when said cutting means contacts said conductor member, and an electrical circuit for actuating said electrically controlled retracting means, said electrical circuit comprising said cutting means and said conductor whose insulation is being stripped, said electrically-controlled retracting means being actuated when said electrical circuit is completed by said cutting means contacting said electrical conductor from which said insulation is being stripped.

3. In a machine for stripping insulation from a conductor having a rotatable shaft, cutting means mounted thereon and rotatable therewith, and actuating means for moving said cutting means into cuttin engagement with the insulation of the conductor being disinsulated, electrical control means causing said actuating means to instantaneously release said cutting means from said cutting engagement upon contact of said cutting means with the conductor being disinsulated, and electrical circuit means for actuating said electrical control means comprising said conductor and said cutting means upon contact of said cutting means with said conductor.

4. A cable stripping machine for removing the insulation from a conductor comprising a rotatable shaft, cutting means mounted thereon, and means for moving said cutting means into cutting engagement with the insulation of the conductor being disinsulated, a collar for mounting said cutting means on said shaft, the outer periphery of said collar having an electrical contact surface insulated from said shaft, collar, and cutting means, electrical contact means insulatingly fixed on said shaft adapted to make electrical contact with the conductor being disinsulated, said contact means and said contact surface being electrically connected, electrically controlled retracting means for instantaneously retracting said cutting means from said cutting engagement upon contact of said cutting means with the conductor being disinsulated, electric control means for actuating said electrically controlled retracting means, and electric circuit means for actuating said electric control means comprising said collar contact surface, said conductor being disinsulated, and said cutting means upon contact of said cutting means with the conductor being disinsulated.

5. A machine for stripping insulation from a conductor comprising a rotatable shaft, a collar thereon, and cutting means mounted on said collar, said shaft, collar, and cutting means being constructed of electrical conducting material, an electrical contact bushing insulatingly fixed on said shaft adapted to make electrical contact with a conductor being disinsulated, an electric contact surface on said collar insulated from said shaft, collar, and cutting means and electrically connected to said contact bushing, a collector brush engaging said contact surface, means for moving said cutting means into cutting engagement with the insulation of a conductor being disinsulated, and electrically controlled means for instantaneously retracting said cutting means from said cutting engagement upon contact of said cutting means with the conductor being disinsulated, and circuit control means for said electrically controlled means comprising said collector brush, contact surface, bushing, conductor being disinsulated, cutting means, collar, and shaft upon contact of said cutting means with the conductor being disinsulated.

6. A machine for disinsulating a conductor comprising a rotatable shaft, cutting means rotatable therewith, and mounting means for mounting said cutting means on said shaft, said mounting means having a contact surface insulated from said cutting means and electrically connected to the conductor being disinsulated, said conductor being insulated from said shaft, contact means engaging said contact surface, electrically operated means for instantaneously retracting said cutting means from cutting engagement with the insulation of the conductor being disinsulated upon contact of said cutting means with said conductor, and electric circuit means for actuating said electrically operated means comprising said contact means, the conductor being disinsulated, and said cutting means upon engagement of said cutting means with said conductor.

7. A device for stripping insulation from a conductor comprising a rotatable shaft, cutting means mounted thereon and rotatable therewith, mounting means for mounting said cutting means on said shaft, said shaft, mounting means, and cutting means being constructed of electrically conductive material, contact means adapted to electrically contact the conductor being disinsulated insulatingly mounted on said shaft and electrically connected to a contact surface on said mounting means insulated from said cutting device, mounting means, and shaft, a contact means engaging said contact surface on said mounting means, solenoid operated means for instantaneously retracting said cutting means from cutting engagement with said insulation upon contact of said cutting means with the conductor being disinsulated, said solenoid operated retracting means being controlled by a thryratron tube circuit means comprising a thyratron tube and relay means, the control grid of said thyratron tube being electrically connected to said contact means engaging said mounting means contact surface, said thyratron tube being conductive and said relay means actuating said solenoid operated means when said cutting means contacts said conductor being disinsulated.

KENNETH J. WELLS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,433,320 Wersel Oct. 24, 1922 2,415,669 Beuschel Feb. 11, 1947 FOREIGN PATENTS Number Country Date 557,307 Great Britain Nov. 15, 1943 

